GeneralHFT - iPhone 5S - No Phone Audio on Calling

I'm trying to set up my iPhone 5S for hands-free telephony in my 4th Generation CR-V for the first time.
My iPhone 5S pairs with the Connect system Bluetooth with no problems for music playback.
It transfers the phone book.
It can make calls.
However when the outgoing call connects there is NO AUDIO.
An "In Call" screen is displayed with "Private Mode" displayed, together with a speaker icon with a slash through it, and a "Transfer" button illuminated. "Touchtones", "Mute" and "Hang Up" are greyed-out.
I suspect there's a box I haven't ticked somewhere, on phone or HFT.
Can anyone help, please?

This can happen if the iPhone is set to only route audio to the phones own mic/speaker (Often pops up as a choice box when connecting) - however it can be just the usual phone-car software muddle.
Try de-registering the iphone from the car in bluetooth settings. Then on the car HFT go into phone settings tell it to forget your phone. Turn off the car . Then reboot the iphone (hold power and round home button simultaneously for about 15 secs or unit the apple log appears. Give it 2 mins or so to turn back on. Then turn on the car and reconnect the phone to the car bluetooth and try again.

It worked!
Thank you, BEA!
The Voice Tag dialling doesn't work, though - it comes up with "Smartphone Voice dialling failed to activate" - but I'm not too bothered by that - I'd feel like an idiot sitting in the car on my own yelling "Home!".
I suppose it's a lot to ask - one set of complex software in the car has to interface with umpteen different flavours of complex smartphone software…
I owe you a glass or two of rouge if you're passing through SW France